Mr Mercer announced his resignation on Tuesday over allegations he was paid to ask questions in Parliament.

He made a statement on the College Green following claims he set up an All-Party Parliamentary Group for undercover reporters posing as lobbyists.

"I argue with nothing the Committee has said or may not have said because I still don't know officially," he said.

"With great heaviness of heart, and I'm hoping the people of Newark will be able to tolerate me in future, I'm hoping they will, I'm going to resign my seat in God's county of Nottinghamshire in the town of Newark.

"I hope that my successor, who has been very carefully chosen, will be the Conservative candidate."

Mr Mercer admitted he was "ashamed" as he apologised for his actions.

Following the resignation, a Conservative spokesman said: "We agree that Patrick Mercer needs to stand down and that there should be a by-election so the people of Newark can have a new MP."

The Newark Conservative Association has confirmed that Robert Jenrick has been selected as the Tory candidate for the by-election.